高性能MIM材料烧结炉的特征及设备主要组成

根据国际和国内MIM材料烧结工艺最新的要求和技术特点,对改进MIM材料烧结炉的结构和排胶方法进行了分析和比较,并对比了MIM烧结使用的真空式批次炉和气氛式连续炉设备性能优缺点,提出了满足市场化要求的技术方案。     

Improved oil treatment conditions for soft degumming

“Soft degumming” is a new physicochemical degumming process. It involves the complete elimination of phospholipids by using a chelating agent, EDTA, in the prescence of an emulsifying additive. To study the optimal cost of the process, a laboratory study was undertaken to find a method based on substituting the emulsifying additive by endogenous phospholipids. The phospholipids were first extracted from the oil by an initial hot-water treatment. In a second stage, a solution containing a chelating agent was incorporated. The mixture was then vigorously stirred to form an emulsion. The degummed oil was obtained after centrifugation. A comparative study carried out on several oils provided an indication of the efficiency of this alternative procedure. The phospholipid content of the processed oils was about 5 ppm phosphorus.     

Degumming of crude soybean oil by ultrafiltration using polymeric membranes

In this study, the ability of two ultrafiltration polymeric membranes to perform the degumming of a crude soybean oil/hexane mixture is tested. The performance of both membranes is defined in terms of their permeation flux, permeate color, and rejection of phospholipids. One of the membranes was synthesized in our laboratories from polyvinylidenefluoride (PVDF); the other one is a commercially available membrane made of polyimide. The degumming experiments were done in a stirred dead-end ultrafiltration cell pressurized with N₂. Results show that tested membranes are suitable for removing phospholipids from the crude oil/hexane miscella in the range of temperature and transmembrane pressure utilized in this work. Both membranes have high selectivity regarding phospholipids and produce a moderate reduction in permeate color. The PVDF membrane gives permeate fluxes up to threefold larger than those obtained with polyimide membrane at the same operational conditions, making the former more suitable for use at industrial scale.     

桑皮纤维的脱胶工艺研究

参考大麻纤维的脱胶工艺,研究了酸温度、酸浓度、碱浓度、煮练时间等对桑皮纤维脱胶效果的影响。结果表明:酸处理温度60℃、酸浓度2.5 g/L、碱浓度1.5 g/L、煮练时间为2 h时,脱胶的效果最佳。     

不同生物酶处理对黄麻纤维的影响

分别用漆酶、纤维素酶、木聚糖酶及果胶酶对黄麻纤维进行脱胶处理,简要分析了各种酶对黄麻纤维脱胶效果的影响,得出了各种酶处理工艺的相对最优工艺参数。各种酶的最优化工艺比较分析结果显示漆酶处理是最有效的脱胶方式。     

香蕉茎秆酶法脱胶工艺及其脱胶纤维性能

为了将生物质废弃物香蕉茎秆进行高值化利用,采用酶法脱胶工艺制备香蕉茎秆纤维。研究超声预处理工艺中频率、处理温度对香蕉茎秆脱胶率的影响,确定较佳的超声预处理工艺。将预处理后的香蕉茎秆粗纤维进行半纤维素酶、果胶酶脱胶,分别考察缓冲液pH、酶浓度、反应温度对脱胶率的影响。结果表明:预处理工艺中超声处理的较佳频率为40 kHz,温度为70℃;酶法脱胶工艺中较佳的半纤维素酶缓冲液pH为5.5,半纤维素酶浓度为0.004 g·ml^-1,反应温度为50℃;较佳的果胶酶缓冲液pH为6.0,果胶酶浓度为0.003 g·ml^-1,反应温度为55℃。采用傅里叶红外光谱(FTIR)、X射线衍射(XRD)和扫描电镜(SEM)分析酶法较佳工艺制备的香蕉茎秆纤维的理化特性;并对其机械性能进行测试与分析。FTIR及XRD结果表明:酶法较佳工艺制备的香蕉茎秆纤维去除了半纤维素和大部分果胶,相对结晶度为66.4%;机械性能测试结果表明酶法较佳工艺制备的香蕉茎秆纤维的拉伸强度、杨氏模量和断裂伸长率分别是118.48 MPa,15.15 GPa,0.67%。     

油脂碱炼水洗废水用于酶法脱胶研究

对油脂碱炼过程中的水洗废水进行循环利用。将油脂碱炼废水进行离心分离,加入毛油中进行水化脱胶,脱出水化磷脂后,进一步进行酶法脱胶,脱出非水化磷脂。通过单因素试验与正交试验,确定废水酶法脱胶的最优工艺条件：水洗废水量2.5%,磷脂酶量30mg/kg,温度55℃,pH4.9,时间3h,搅拌速度90r/min。在最优条件下进行脱胶实验,测定脱胶油中的磷含量为4.9mg/kg,说明水洗废水可以替代软化水用于脱胶工序,每千克成品油可节省热量34～36kJ,提高得率0.2% 以上。     

餐余地沟油脱胶条件的优化研究

采用混合酸-碱-水联合脱胶法,对餐余地沟油中的胶体物质进行处理和去除,并对脱胶条件进行了确定和优化。得到的最佳脱胶条件为:0.3%柠檬酸和0.4%磷酸组成混合酸溶液,在85℃下搅拌反应30 min,然后45℃下用10%的氢氧化钠溶液控制溶液p H为5～6反应30 min,最后加入油脂质量3%的蒸馏水,75℃下搅拌反应30 min,恒温静置2 h,2 000 r/min离心5 min。在最佳的脱胶条件下,对5种常见的地沟油进行脱胶处理,脱胶率最高可达97.37%。     

米糠油脱胶和酸化凹凸棒土脱色工艺研究

采用正交实验研究了米糠毛油脱胶工艺,得到的酸法脱胶工艺最佳条件为磷酸添加量0.3%、脱胶温度70℃、加水量3%、反应时间40 min,此时米糠油脱胶率为87.7%。在此基础上,采用单因素实验考察了酸化凹凸棒土添加量、脱色温度、脱色时间对脱色率的影响。结果表明:在酸化凹凸棒土添加量5%、脱色温度110℃、脱色时间30 min条件下,米糠油脱色率达到96.6%。